In commercial fishing operations, the method of fishing known as purse seine fishing is an effective and widely used technique. The method is conceptually simple. A seine, or net, is fitted at one end with buoyant devices (e.g. floats) and at the other end with weighting devices (e.g. sinkers). As the seine is deployed in a rough circle, the weighted end of the seine submerges to cause the seine to hang essentially vertically in the water. To provide for seine retrieval, a purse line is attached to the weighted end of the seine by a plurality of connectors, known as purse rings. As the purse line is tightened by fishermen on the fishing vessel, the weighted end of the seine is drawn together to enclose fish within the seine. The weighted end, now pursed, is raised and drawn toward the fishing vessel. Simultaneously, support craft retrieve and draw in the buoyed end of the seine. In this way, fish are trapped in the seine as it is retrieved.
During seine retrieval, the purse line, through its interaction with the purse rings, is used to both purse the seine and draw it toward the fishing vessel. As can be easily imagined, the forces which are generated between the purse line and the purse ring during these operations can be very substantial. Indeed, these forces can cause significant frictional erosion and wear on both the purse line and the surface of the purse rings. The eventual results are a complete failure of the purse rings and a fraying of the purse line which causes the purse line to snag on the netting. In either event, the operation is compromised and the purse rings may need to be replaced.
Recent developments in the commercial fishing area have compounded the problem of purse ring wear because many of the now preferred fishing grounds are located in the Western Pacific Ocean. It happens that purse seiner operations in the Western Pacific require deeper deployment of the seines than thermoclines in the Western Pacific often result in deeper schooling of food fish. Consequently, with the deployment of seines, the forces required to retrieve the seines (e.g. forces between the purse line and the purse rings) are greatly increased. As a further consequence, standard purse rings, such as are used in other oceans of the world, are generally inadequate for use in the Western Pacific.
In light of the foregoing, the present invention recognizes the need to significantly reduce purse ring wear to permit efficient seiner operations at greater depths in the ocean and to prolong the useful life of purse rings used in seiner operations regardless of depth. It is therefore an object of the present invention to provide a purse ring for use in purse seiner fishing operations which has a relatively long period of usefulness. It is a further object of the present invention to provide a purse ring for seiner operations that reduces frictional wear on the purse ring when a purse line is drawn through it during seine retrieval operations. It is yet a further object of the present invention to provide a purse ring for use in purse seiner operations that facilitates purse line insertion into or withdrawal from the purse ring. Another object of the present invention is to provide a purse ring for purse seiner fishing operations which is easy to install and use, relatively easy to manufacture, and comparatively cost-effective.